The present application relates to a semiconductor structure and a method of forming the same. More particularly, the present application relates to a semiconductor structure including a material stack of, from bottom to top, a semiconductor seed material that is substantially relaxed and defect-free, and a high-mobility semiconductor channel material that is also defect-free.
For more than three decades, the continued miniaturization of metal oxide semiconductor field effect transistors (MOSFETs) has driven the worldwide semiconductor industry. Various showstoppers to continued scaling have been predicated for decades, but a history of innovation has sustained Moore's Law in spite of many challenges. However, there are growing signs today that metal oxide semiconductor transistors are beginning to reach their traditional scaling limits. Since it has become increasingly difficult to improve MOSFETs and therefore complementary metal oxide semiconductor (CMOS) performance through continued scaling, further methods for improving performance in addition to scaling have become critical.
One technique for improving device performance is to provide MOSFETs that are formed upon a channel that is composed of a high-mobility semiconductor material such as, for example, germanium or an III-V compound semiconductor. Aspect ratio trapping (ART) is touted as a viable approach for providing high-mobility semiconductor channel materials. Conventional ART includes first forming a defective semiconductor seed layer in a trench to relax the strain and thereafter the channel material is grown on the defective semiconductor seed layer. In ART, the defects are trapped in the semiconductor seed layer and the channel layer is defect-free.
Conventional ART processes however have some drawbacks associated therewith. For example, the defective semiconductor seed layer has to be isolated from the device layer which is not trivial to achieve without requiring complicated processes. Moreover, and in conventional ART processes, a small number of defects may propagate from the semiconductor seed layer into the overlying channel material, rending manufacturability of conventional ART questionable.
As such, there is still a need for providing a method of forming high-mobility semiconductor channel materials that avoids the drawbacks associated with conventional ART processes.